In construction it is frequently necessary to provide occasional access to valves, switches, punch-down blocks, and the like that are behind the wall or ceiling. Such a door typically comprises an outer frame that is permanently set in the wall and an inner frame and panel that are secured to the outer frame by hinges along one edge and a releasable latch along an opposite edge. The access door need not be complex, as it is used infrequently, but must be unobtrusive when installed, that is typically be flush so it can be finished like the wall, and centered in its opening so it presents a nice appearance.
Thus a standard access door comprises as described in German patent 37 36 060 or EP 0,567,731 a pair of annular L-section frames, one within the other. The outer wall frame is typically set permanently in the wall, and the inner panel frame is adapted to hold a wall or ceiling panel and is releasably retained in the wall frame by some sort of hinge/latch assembly. In a typical installation the panel frame is adapted to hold one or two thicknesses of standard gypsum board, with in some instances a thin steel plate on the back face of the inset panel. The frames are formed with centering bumps that keep the inner frame at a uniform spacing withing the outer frame.